This invention relates to an automatic punching machine for making brushes and to a method for automatically making brushes by punching.
The invention addresses the technical field of systems for the production of brushes composed of a brush body having a plurality of openings into which bundles of fibers, or bristles, are inserted and fixed.
More specifically, the invention relates to automatic machines for making industrial brushes. The invention, however, also relates to automatic machines for making brushes in general (for example, brushes for dental use).
These machines are equipped with a plurality of movable elements driven in coordinated fashion in a cyclic work sequence. The movable elements act in conjunction to insert and fix the bundles of fibers in the brush body.
More specifically, automatic punching machines have the following movable elements:                a slide (also known as “punch”) movable with reciprocating motion for receiving bundles of fibers and feeding them to a brush body;        a needle movable with reciprocating motion for inserting the bundles of wires into corresponding openings of the brush body;        a device (also known as “bow”) for removing the bundles of fibers from a tank of these fibers;        a feeder (also known as “wire feeder”) for feeding fixing material (usually consisting of metal wire), acting in conjunction with the slide and with the needle to allow insertion of a quantity of fixing material into the opening of the brush body together with a corresponding bundle of fibers;        a cutting device (also known as “cutter”) designed for cutting portions of fixing material;        a shaping device (also known as “frame”) for shaping fixing elements comprising a predetermined quantity of fixing material;        a device for separating fibers (also known as “bristle separator”).        
Each of these movable elements is reciprocatingly driven from a first operating position to a second operating position, in each working cycle (or punching cycle).
Generally speaking, all of the above mentioned movable elements are driven by a single shaft through the agency of a plurality of cams. Thus, there is a motor (for example, an electric motor) which drives the shaft and which, consequently, drives all the movable elements.
This solution guarantees perfect synchrony between the movements of all the movable elements and makes the machine particularly fast.
This “mechanical” solution is not, however, very flexible and suffers from considerable problems if the machine needs to be adapted to making brushes of different sizes, especially with fibers (that is, bristles) of different lengths.
In effect, changing over to brushes with bristles of a different length means adjusting the stroke of one or more of these movable elements. That makes changeovers in a machine of this kind relatively tricky.
In light of this, other technical solutions have been developed where one or more of the movable elements are driven by a dedicated actuator, for example an electric motor used for driving a single movable element.
A solution of this kind is described in patent document EP1493355B1.
Further, to facilitate changeover, the Applicant has developed a technical solution (described in patent document WO2011045743) where the electrical actuators are connected to respective movable elements by kinematic mechanisms which make it easier to adjust the stroke of the movable elements.
These solutions also have drawbacks, however, linked to the difficulty of coordinating and synchronizing the movement of a plurality of movable elements driven by corresponding actuators. This difficulty is emphasized by the need to make the machine particularly efficient in terms of speed and reliable against malfunctions.
Another disadvantage of these solutions is their very high energy consumption.